The Sky Blues secured all three points in their final group game in the Leasing.com Trophy thanks to a Max Biamou hat-trick.
The striker scored all three goals for City, as they found a winner with seconds left on the clock against Southampton U21s.
The win means City will have to wait on the final group fixture between Walsall and Forest Green Rovers to see if they will qualify for the next round.
It was a quiet start to proceedings, with both sides battling for possession early on, with the Sky Blues looking to take hold of the game.
The Sky Blues did create the first opening of the game and it was a good move down the right starting with Tennai Watson and he found Bapaga who teed up Jordan Shipley, but the midfielder’s shot was dragged wide.
City took control of the game and were pushing for an opener and 20 minutes in a ball into the box by Shipley is met by the head of Drysdale, but his effort is held onto by Harry Lewis.
Moments later and the Saints defence was carved open by a Liam Walsh through ball as he picked out the run of Biamou, but the striker’s shot was saved.
The visitors had their first chance of the game and it was Kameron Ledwidge with the opportunity, but he dragged his shot well wide.
Harlem Hale was the first Saints man to test Ben Wilson, but it was easy for the City ‘keeper as the ball rolled comfortably into his arms.
Max Biamou came closest to finding an opener when he curled an effort towards goal from the edge of the area, but his effort was expertly saved by Lewis.
HALF-TIME: Sky Blues 0-0 Southampton U21
It didn’t take City long to find the opener after the break however, and it was Biamou who fired home after he played a one-two with Josh Eccles and then left Lewis helpless.
The striker scored again minutes later and this time it was from the spot after Will Bapaga was brought down in the area, Max stepped up and sent the ‘keeper the wrong way.
However, the visitors pulled one back on the hour mark and it was another penalty and the Saints captain Callum Slattery stepped up and just squeezed it past Ben Wilson.
City almost restored their two-goal advantage when Liam Walsh rattled the post with a volley from outside of the area.
Wilson pulled off a good stop as the Saints created a chance outside of the area, but he was able to tip the shot over the bar.
At the other end, Kyle McFadzean tested Lewis with a fine header from inside the area, but the ‘keeper made a good stop.
However, with five minutes remaining, the visitors grabbed an equaliser through Slattery again, as his shot from distance beat Wilson.
But with seconds remaining, Max Biamou completed his hat-trick with a thunderbolt inside the box, beating Lewis and earning the Sky Blues all three points.
FULL-TIME: Sky Blues 3-2 Southampton U21s
Yellows: Pascal Kpohomouh 74’
Goals: Max Biamou 52’ 55’ 94’, Callum Slattery 61’ 84’
Attendance: 375 (7)
Sky Blues Xl: Ben Wilson (GK), Tennai Watson (Dabo 46’), Declan Drysdale, Kyle McFadzean (C), Brandon Mason, Liam Walsh, Josh Eccles, Jordan Shipley, Will Bapaga, Gervane Kastaneer (Young 86’), Max Biamou.
Unused Subs: Marko Marosi (GK), Dom Hyam, Jonny Ngandu, Jack Burroughs, David Bremang.
Southampton Xl: Harry Lewis (GK), Callum Slattery (C), Kayne Ramsay, Aaron O’Driscoll, Harlem Hale (Hansen 61’), Kameron Ledwidge, Alex Jankewitz, Christian Norton, Pascal Kpohomouh, Kegs Chauke (Defise 74’), Kazeem Olaigbe.
Unused Subs: Jack Bycroft (GK), Kieran Freeman, Jack Turner, James Morris, Sam Bellis.